Using a series of cell variants derived from the Chinese Hamster Ovary (CHO) cell line we have thoroughly investigated the phenomenology and some of the biochemistry of the molecular basis of Con A-initiated receptor site mobility. In the proposal presented here we have put forth an hypothesis to explain the lack of lectin receptor mobility in the H-7w CHO subclone grown in 1mM dBcAMP. This model postulates a passive restraint to mobility by suggesting that the Con A receptors of H-7w cells grown in dBcAMP are unable to associate with membrane bound actin. We have devised a technique to investigate the role of Con A in enhancing Con A receptor interaction with actin which is based on the relative solubility of the Con A receptors in Triton X-100 when isolated membranes are incubated with Con A. We will use this isolated membrane system to identify Con A receptors with different Ka's, to investigate the molecular mechanisms underlying positive cooperativity in Con A binding to the cell surface, and to further characterize the mechanism(s) whereby Con A binding to the cell surface modifies the availability of sialic acid residues on the cell surface. After isolating the majority of the major Con A receptors we intend to prepare antibodies against individual Con A receptors. We will use these antibodies to study the control of mobility of individual Con A receptors, to further characterize the mechanism(s) underlying the distribution of individual Con A receptors to the dorsal or ventral surface of substratum-attached cells and to isolate cell variants lacking one or more Con A receptors. The cell variants will be used to further study the Con A-detectable phenotypes as well as to investigate the role of individual Con A receptors in such biologically important phenomena as cell-cell and cell-substratum adhesion.